Vehicles include a powertrain that is comprised of an engine, multi-speed transmission, and a differential or final drive. The engine produces a torque, and the multi-speed transmission increases the overall operating speed range of the vehicle by permitting the engine to operate through its torque range a number of times. The multi-speed transmission may include any of several different styles of multi-speed transmission, including automatic transmissions, continuously variable transmissions manual transmissions, or dual clutch transmissions.
Dual clutch transmissions include a gearbox having a plurality of gears that are selectively combined to define a plurality of gear ratios. The plurality of gear ratios may be broken into a plurality of odd gear ratios and a plurality of even gear ratios. The odd gear ratios may define a first gear ratio, a third gear ratio and a fifth gear ratio. The plurality of even gear ratios may include a second gear ratio, a fourth gear ratio and a sixth gear ratio. The dual clutch transmission includes a clutch assembly having two separate clutches, a first clutch and a second clutch, to selectively drive the gear ratios. The first clutch drives the odd gear ratios, and the second clutch drives the even gear ratios. Shifting between the gear ratios may be accomplished while minimizing interruption of torque distribution to the differential by applying the torque from the engine to one clutch at the same time as the torque is being withdrawn from the other clutch.
The clutch assembly may include a wet clutch assembly. If the clutch assembly is a wet clutch assembly, the first clutch and the second clutch each include wet multi-plate clutches that are bathed in oil. If the clutch assembly is a wet clutch assembly, then the dual clutch transmission may be referred to as a wet dual clutch transmission.
Several of the operations of the wet dual clutch transmission are hydraulically controlled through a valve body. The valve body operates as a hydraulic control center that receives pressurized fluid from a main fluid pump. The pressurized fluid coming from the main fluid pump is regulated, and is used to control at least one hydraulically controlled component of the wet dual clutch transmission. The hydraulically controlled component of the wet dual clutch transmission may include, but is not limited to, actuation of the wet clutch assembly, control of a lube regulating valve for the wet clutch assembly, control of an on/off solenoid, actuation of a synchronizing shift fork, or actuation of a line pressure control valve.